TW202005301A - Antenna system and resetting method therefor - Google Patents

Abstract

An antenna system includes a plurality of antennas, a switching unit, a communication unit, and a control unit. The communication unit receives each reference value which corresponding to each antenna via each switch in the switching units that is turned on. The control unit receives the reference values from the communication unit and compares each of which with an alarm threshold. The control unit output the restart command for restarting the switching unit when the reference value does not meet expectations. A resetting method for antenna system is also disclosing.

Description

Antenna system and its restart method

This case is about an antenna system.

With the advancement of technology, many types of electronic devices are often equipped with wireless communication components. However, under different environmental influences, such as when the human body is close to the antenna, the distance from the base station is far away or the direction is offset, and the room wall is blocked, etc., it will affect the coverage rate of the multi-antenna radiation field pattern, which will cause the communication device to have certain angle The communication ability on the Internet is weak or the communication corners, which in turn affects the user's feelings.

This case is to provide an antenna system including: a plurality of antennas, a switching unit, a communication unit and a control unit. The switching unit has a plurality of switches, and each switch and the corresponding antenna are in an on state or an off state. The communication unit is connected to each switch of the switch unit to couple with each antenna through each switch. The communication unit receives the corresponding reference value set of each antenna from the switches in the conducting state. The control unit connects the switching unit and the communication unit. The control unit receives each reference value group from the communication unit and compares the reference value group with the alarm threshold to determine whether any of the reference value groups meets expectations. When the reference value group does not meet expectations, a restart instruction is output to restart the switching unit.

This case is to provide another method for restarting an antenna system, which includes: receiving a reference value group from an antenna corresponding to at least one switch in an on state in a switching unit; comparing the reference value group with an alarm threshold To determine whether the reference value group meets expectations; and when the reference value group does not meet expectations, output a restart command to restart the switching unit.

According to the above, according to the comparison between the return value of each antenna and the alarm threshold, the present invention can further restart the antenna system to further drive the switch in the switching unit to change to the off state or the on state. In this way, a suitable antenna can be found to maintain an appropriate radiation field pattern, so that the quality of good wireless transmission can be maintained at any time, so that the user can further maintain the feeling of using it.

Referring to FIG. 1, the antenna system includes multiple antennas 10, a switching unit 20, a communication unit 30 and a control unit 40. Each antenna 10 is connected to the switching unit 20. The control unit 40 is connected to the switching unit 20 and the communication unit 30 respectively. The communication unit 30 is also connected to the switching unit 20.

In one embodiment, each antenna 10 is used to send and receive wireless signals, and thus can receive or output data. In FIG. 1, five antennas 10 (101, 102, 103, 104, 105) are used as an example for illustration, but in the present invention, the number of antennas 10 is not limited.

In some embodiments, each antenna 10 may be an omnidirectional antenna, a directional antenna, or other types of antennas, but not limited thereto.

Please refer to FIG. 1 and FIG. 2A, the switching unit 20 has a plurality of switches 21, and the switches 21 correspond to the antennas 10 respectively. When the switch 21 is in a conducting state, the switch 21 is electrically connected to its corresponding antenna 10. When the switch 21 is in an open state, the switch 21 and its corresponding antenna 10 are not conducting. In this embodiment, at least one of the switches 21 in the switching unit 20 is in a conducting state. In this embodiment, the switches 212 and 213 are in the on state, and the remaining switches 211, 214 and 215 are in the off state, but not limited to this.

The antenna 10 can transmit the received wireless signal to the communication unit 30 via the switch 21 in the conductive state, or the communication unit 30 can transmit the data to the corresponding antenna 10 via the switch 21 in the conductive state for further wireless Output data.

In one embodiment, the number of switches 21 corresponds to the number of antennas 10. In other words, the total number of antennas 10 is the same as the total number of switches 21. Here, in FIG. 1, five switches 21 (211, 212, 213, 214, 215) are used as an example for description, but in the present invention, the number of switches 21 is not limited thereto.

In FIG. 1, the switches 212 and 213 are in the on state, and the remaining switches 211, 214 and 215 are in the off state. Therefore, the antennas 102 and 103 corresponding to the connection switches 212 and 213 transmit the received wireless signal to the communication unit 30.

The communication unit 30 receives the reference value set from the antennas 102, 103 corresponding to the switches 212, 213 in the on state of the switching unit 20 (step S01). Next, the communication unit 30 transmits the received reference value set to the control unit 40.

Referring to FIGS. 1 to 4, the control unit 40 compares the received reference value groups with the alarm threshold to determine whether the reference value groups meet expectations (step S02). When it is determined that at least one of the reference value groups does not meet expectations, the control unit 40 outputs a restart instruction to restart the switching unit 20 (step S03). When the switching unit 20 is restarted, the switching unit 20 switches all the switches (211 to 215) to the conducting state (as shown in FIG. 3) according to the restart instruction (ie, step S031 in FIG. 2B). Next, the control unit 40 receives the return value from the antenna 10 corresponding to each switch 21 from the communication unit 30 (ie, step S032 in FIG. 2B ). A selection command is generated according to at least one of the better return values and sent to the switching unit 20 (ie, step S033 in FIG. 2B). In detail, the control unit 40 sorts all the received return values to generate a sorting result, and selects at least one of the better return values according to the sorting result (for example: sorting is earlier Return value) and generate the corresponding selection instruction.

After the control unit 40 transmits the selection command to the switching unit 20, the switching unit 20 selects the corresponding switch 21 according to the selection command and maintains it in the on state, and switches the remaining switches 21 to the off state (as shown in FIG. 4) (That is, step S034 in FIG. 2B). In this embodiment, please refer to FIGS. 3 to 4, after the control unit 40 sorts all the return values, it can know that the return values of the antennas 101 and 104 corresponding to the switches 211 and 214 are the five switches 21 The top 2 of the corresponding antennas. Therefore, the control unit 40 can generate a corresponding selection instruction according to the sorting result. The switching unit 20 maintains the switches 211 and 214 in the on state according to the selection instruction, and switches the switches 212, 213 and 215 in the off state.

In some embodiments, the selection command generated by the control unit 40 is able to select one of the switches 21 to be maintained in the on state, and make the remaining switches 21 in the off state. In other embodiments, any combination of the switches 21 may also be selected to form a conductive state. It can be adjusted according to actual needs.

When the selection command is to select one of the switches 21 to be turned on, it means that the control unit 40 sorts the returned values and selects the best one in the sorted result (the sorted first one), and maintains the corresponding best The switch 21 of the return value (that is, the one corresponding to the best return value selected from the switch 211 to the switch 215) is in the on state, and switches the remaining switch 21 to the off state.

After the control unit 40 sends the selection command, please refer to FIG. 2A again, the control unit 40 can receive the reference value group of the antenna in the conductive state from the communication unit 30 after an interval time (ie, repeat step S01) for the control unit 40 can again judge whether its reference value group meets the alarm threshold (ie execute step S02). When it is determined that the reference value group does not meet the alarm threshold, a restart instruction is generated again to restart the switching unit 20 (ie, step S03).

In an embodiment, the control unit 40 presets a plurality of restart time points, that is, the control unit 40 outputs a restart instruction according to the restart time point to drive the switching unit 20 to restart. Wherein, each time the switching unit 20 is restarted, the control unit 40 records the sorting results of the return values of each antenna 10 each time, and analyzes the changes of the multiple return values of each antenna 10 according to the sorting results. And according to the change of the return value of each antenna, the time interval between more efficient restart time points is calculated. For example, and referring to FIG. 5, the X axis is the standby time T ₁ and the Y axis is the restart time interval T ₂ of the switching unit 20. In an embodiment, as the standby time becomes longer, the time interval between restart time points may be increased in a multiple time interval T _b (such as 30 minutes, 1 hour, 2 hours, etc.). In this embodiment, when the time interval between the preset restart time points is 30 minutes, the control unit 40 records the sorting result of each return value every time according to the restart command every 30 minutes. (If there are three occurrences) When the sorting result of the return value has not changed, the control unit 40 will postpone it to one hour after the preset restart time point of the next time (ie the fourth time). Conversely, if the control unit 40 changes the order of the return values recorded when the restart command corresponds to the preset restart time point, the control unit 40 maintains the preset restart time point to output the restart command.

Similarly, as the standby time becomes longer, the time interval between restart time points may increase in an exponential time interval T _c (such as 30 minutes, 1.5 hours, 4 hours, etc.), thereby reducing the number of times the switching unit 20 is restarted. When the antenna system is placed in a stable environment, the calculation load of the control unit 40 can be reduced.

In an embodiment, if the selected antennas are the same antenna after multiple restart steps, the control unit 40 may set the time interval between restart time points to a multiple time interval T _b or exponential time as described above mode interval T _c increases.

In one embodiment, the time interval between restart time points has a maximum time interval T _d . For example, the maximum interval of the control unit 40 is set to 12 hours. When the control unit 40 increases the preset restart time length according to the foregoing manner, the time interval between the restart time points is at most equal to the maximum time interval T _d .

Here, regarding the detailed content of the control unit 40 after receiving the reference value group and making a judgment, the following describes several embodiments.

In the first embodiment, referring to FIG. 1, the switches 212 and 213 in the switching unit 20 are in an on state, and the switches 211, 214 and 215 are in an off state. Therefore, the communication unit 30 can individually receive the reference value sets of the antennas 102, 103 via the switches 212, 213 (step S01). The reference value group is the signal strength of the wireless signals received by the antennas 102 and 103 individually, such as RSSI (Received Signal Strength Indicator) value, Ping value, or other indicators related to signal strength.

In the first embodiment, the reference value group is taken as an RSSI value as an example. When the communication unit 30 receives the wireless signals from the antennas 102 and 103, it will obtain the first RSSI value (ie the first reference value set) from the wireless signal of the antenna 102 and the second RSSI from the wireless signal of the antenna 103 Value (ie the second reference value group) (step S01). Next, the communication unit 30 transmits the first reference value group and the second reference value group to the control unit 40. Next, the control unit 40 determines whether any of the first reference value group and the second reference value group is lower than the alarm threshold (as shown in steps S021 and S022 of FIG. 6 ). That is, the control unit 40 determines the size of the first reference value group (for example, the first RSSI value = -85 dBm) and the preset alarm threshold (for example, the preset RSSI value = -80 dBm). In this embodiment, the first reference value group is less than the alarm threshold. This means that the signal strength of the wireless signal received by the antenna 102 is weakened. The control unit 40 generates a restart instruction (step S03). Then the control unit 40 transmits a restart instruction to the switching unit 20. The switching unit 20 switches all the switches 21 to the conducting state according to the restart instruction (step S031) (as shown in FIG. 3). Then, the control unit 40 can receive the corresponding return value (RSSI value) of each antenna 10 from the communication unit 30 (step S032), and sort the return values. According to the sorting result, the switch 21 (the switches 211 and 214 in this embodiment) corresponding to the highest value return value is selected (as shown in FIG. 4) to generate a selection instruction (step S033). Therefore, the switching unit 20 maintains the switches 211, 214 in the on state according to the selection instruction, and switches the switches 212, 213, 215 to the off state (as shown in FIG. 4) (step S034). Conversely, when the control unit 40 determines that the first reference value group and the second reference value group are equal to the alarm threshold value, the control unit 40 does not output a restart instruction. In this way, the antenna system can maintain good wireless transmission quality, which can further allow users to maintain their good experience.

In an embodiment, when the control unit 40 determines that the first reference value group (for example, the first RSSI value = -75 dBm) is greater than the alarm threshold, its determination result is in line with expectations. Then the control unit compares the second reference value group (for example, the second RSSI value = -85 dBm) with the alarm threshold (for example, the preset RSSI value = -80 dBm) to determine whether the second reference value group meets expectations (as shown in the figure 6 Step S022). In this embodiment, because the judgment result of the second reference value group and the alarm threshold is not in line with expectations, the control unit 40 will output a restart instruction to the switching unit 20 to restart the switching unit 20 (as shown in step S03 of FIG. 6) . The switching unit 20 switches each of the switches 21 to the conducting state according to the restart instruction (as shown in FIG. 3 ), and receives the corresponding return value (RSSI value) of each antenna 10 for sorting. In addition, the corresponding selection command can be generated to drive the corresponding switch 21 into the on state and the off state.

Among them, the order of judging the reference value group and the alarm threshold is not limited in the present invention. This means that it can be judged first whether the second reference value group and the alarm threshold are in line with expectations, and then whether the first reference value group and the alarm threshold are in line with expectations.

Please refer to FIGS. 1 and 2A. In an embodiment, the reference value group includes a front reference value and a back reference value. The alarm threshold may be a degree of decrease in signal strength. Taking the first embodiment as an example, the alarm threshold may be the degree of decrease in the RSSI value. In other words, the control unit 40 will obtain the RSSI value of the antenna 102 corresponding to the switch 212 in the on state at the first time point (earlier time point) (that is, the previous reference value = -69 dBm), and the second At the time point (later time point), the RSSI value of the antenna 102 corresponding to the switch 212 in the same conduction state is obtained (ie, the rear reference value = -75 dBm). Then, calculate a difference between the pre-reference value and the post-reference value (for example, the difference between the post-reference value and the pre-reference value), and compare this difference with the alarm threshold to determine whether it meets expectations. For example, the preset alarm threshold is -5 (that is, the preset RSSI reduction degree is 5). When the difference between the current reference value and the back reference value (for example, the difference is -6) is less than the alarm threshold (indicating that the RSSI value of the antenna 102 has decreased by more than 5), it means that the signal strength of the wireless signal received by the antenna 102 has changed Weak phenomenon. Therefore, the control unit 40 immediately outputs a restart instruction to restart the switching unit 20.

In an embodiment, when the reference value group received by the communication unit 30 is the Ping value of the wireless signal, it may be used to determine whether the reference value group and the alarm threshold are in line with expectations. That is, when the control unit 40 determines that any one of the Ping values is greater than the alarm threshold, it generates a restart instruction. Conversely, when it is judged that each Ping value is less than or equal to the alarm threshold, it indicates that the antenna 10 corresponding to the switch 21 of the on state is of good wireless transmission quality, which can further allow the user to maintain its good experience . In some embodiments, other methods for determining the signal strength are also as described above, and will not be repeated here.

In an embodiment, during the restarting process of the switching unit 20, when the return value (for example: RSSI value) of each antenna 10 received by the control unit 40 does not match the expected alarm threshold, in order to allow the antenna system to continue When communicating, the antenna 10 with the better return value will be selected from all the return values that do not meet the expected return value, which will cause the switching unit 20 to be restarted all the time.

Therefore, when the switching unit 20 restarts several times in succession (for example: 3 times), the return value (RSSI value) of each antenna 10 received by the control unit 40 each time does not meet the expected value compared with the alarm threshold, it will Start an alarm threshold adjustment procedure.

In an embodiment, the alarm threshold adjustment procedure is that the control unit 40 adjusts the alarm threshold to the optimal return value among the return values of each antenna 10, or adjusts the alarm threshold to the optimal return value One less difference (for example: a difference of 5, which means lowering the alarm threshold), to avoid that all antennas 10 in the current environment are not as expected as compared with the alarm threshold, which causes the switching unit 20 to continuously restart, causing unnecessary System load.

1 and 2A, in one embodiment, the communication unit 30 uses the connection time of the antenna 102 extracted from the received wireless signal as a reference value group. That is, the period during which the antenna 102 transmits the wireless signal is called the connection time. In this embodiment, the control unit 40 sets a preset connection time as an alarm threshold. Next, the control unit 30 compares whether the connection time is consistent with the preset connection time (ie, step S02). When the connection time is less than the preset connection time, it outputs a restart command (ie, step S03). In this embodiment, when the antenna 102 is momentarily disconnected or abnormal and the connection time is suddenly reduced, it may indicate that the wireless communication quality of the antenna 102 is not good, so restart the switching unit 20 to select wireless communication Good quality antenna, so that users can maintain a good experience.

Please refer to FIG. 1 again. The control unit 40 further includes a sensing module 41. The sensing module 41 includes a positioning element 411, which can be used to communicate with a global positioning system (GPS; Global Positioning System) to obtain current positioning information. As a reference value group. In this embodiment, the control unit 40 sets the previous positioning information as an alarm threshold, and compares the current positioning information with the previous positioning information. If the current positioning information is different from the previous positioning information (that is, the reference value group does not meet expectations), it is judged that the antenna system has a moved position. In this way, the control unit 40 will generate a restart instruction to restart the switching unit 20.

In one embodiment, the sensing module 41 includes a gravity sensing element 412, which can sense whether the antenna system has any dynamic changes such as flip, movement, angle change or other arbitrary changes to generate a current gravity sensing information as A system status reference value. In this embodiment, the control unit 40 sets the previous gravity sensing information as an alarm threshold, and compares the current gravity sensing information with the previous gravity sensing information. If the current gravity sensing information is different from the previous gravity sensing information (that is, the system state reference value does not meet expectations), it is determined that the antenna system has a dynamic change such as flip, movement, angle change, or other arbitrary changes. In this way, the control unit 40 will generate a restart instruction to restart the switching unit 20.

In an embodiment, the gravity sensing element 412 may be a gravity sensor (G-Sensor), a gyroscope, or a combination thereof, and the invention is not limited thereto.

According to the above-mentioned embodiment, whether the comparison between the reference value set of each antenna 10 and the alarm threshold meets expectations, the switching unit 20 can be further restarted to drive each switch 21 to change to the open state or the conductive state again. In this way, appropriate antenna patterns 10 can be used to maintain an appropriate radiation pattern at any time, so that good quality of wireless transmission can be maintained at any time, so as to further enable users to maintain their feeling of use. Furthermore, by intelligently changing the alarm threshold, the switches 21 can be switched more accurately and the user can get a better experience.

10‧‧‧Antenna 101-105‧‧‧Antenna 20‧‧‧switch unit 21‧‧‧switch 211-215‧‧‧switch 30‧‧‧communication unit 40‧‧‧control unit 41‧‧‧sensing Module 411‧‧‧positioning element 412‧‧‧gravity sensing element S01-S03‧‧‧step S021-S022‧‧‧step S031-S034‧‧‧step T1‧‧‧standby time T2‧‧‧restart time interval Tb‧‧‧multiple time interval Tc‧‧‧ exponential time interval Td‧‧‧ maximum time interval

[FIG. 1] is a schematic structural diagram of an embodiment of the antenna system of the present case. [Figure 2A] is a step diagram of one method of restarting the antenna system in this case. [Figure 2B] is a diagram of the restart procedure of the antenna system restart method in this case. [Figure 3] is a schematic diagram of the restart process of the antenna system in this case. [FIG. 4] It is a schematic diagram of an embodiment of the antenna system of this case after restarting. [Figure 5] It is a schematic diagram of the time interval of the restart time point of the antenna system in this case. [Fig. 6] is a schematic diagram of steps of the first embodiment of the antenna system of the present case.

10‧‧‧ Antenna

101-105‧‧‧ antenna

20‧‧‧Switch unit

21‧‧‧Switch

211-215‧‧‧Switch

30‧‧‧Communication unit

40‧‧‧Control unit

41‧‧‧sensing module

411‧‧‧Locating element

412‧‧‧Gravity sensing element

Claims (18)

An antenna system includes: a plurality of antennas; a switching unit having a plurality of switches, and each of the switches and the corresponding antenna is in an on state or an off state; a communication unit is connected to the switching unit Each of the switches is coupled to the antennas through the switches, the communication unit receives a corresponding reference value set of the antenna from the switch in the on state; and a control unit is connected to the The switching unit and the communication unit, the control unit receives the reference value group from the communication unit, and compares the reference value group with an alarm threshold to determine whether the reference value group meets expectations, when the reference value group is not When it meets expectations, a restart command is output to restart the switching unit. The antenna system as described in claim 1, wherein when the switching unit is restarted, the switches are all switched to the conductive state, and the control unit receives a return value of each of the antennas and based on the At least one of the better return values generates a selection command and sends it to the switching unit. The switching unit selects the corresponding switch according to the selection command and maintains the on-state of the switch, and the remaining ones The switch is switched to this open state. The antenna system as described in claim 2, wherein when the switching unit is restarted, the control unit sorts the return values to generate a sort result, and selects the return values according to the sort result At least one of the earlier rankings generates the corresponding selection instruction. The antenna system as described in claim 2, wherein the return value of each of the antennas received by the control unit each time the switching unit is continuously restarted several times is not as expected as compared with the alarm threshold Time, an alarm threshold adjustment procedure is started. The antenna system as described in claim 1, wherein the control unit further includes a positioning element, the positioning element communicates with a global positioning system to obtain a current positioning information as the reference value group, the control unit will perform a previous The positioning information is set to the alarm threshold, and the current positioning information is compared with the previous positioning information. When the current positioning information is different from the previous positioning information, the restart instruction is generated. The antenna system as described in claim 1, wherein the control unit further includes a gravity sensing element that senses a dynamic change of the antenna system to generate a current gravity sensing information as a system state reference value , The control unit sets the previous gravity sensing information as the alarm threshold, and compares the current gravity sensing information with the previous gravity sensing information, when the current gravity sensing information and the previous gravity sensing information If the sensing information is different, the restart command is generated. The antenna system as described in claim 1, wherein the reference value group includes a front reference value and a rear reference value, the alarm threshold is a degree of decrease corresponding to the reference value group, and the control unit Obtain the pre-reference value, the control unit obtains the post-reference value at a second time, the control unit calculates a difference between the pre-reference value and the post-reference value, and compares the difference value with the alarm threshold It is judged whether the difference is in line with expectations, and the restart instruction is generated when it is judged that the difference is not in line with expectations. The antenna system as described in claim 1, wherein the reference value group is a connection time of the antenna corresponding to each, the alarm threshold is a preset connection time, and the control unit compares the connection time with the The preset connection time is compared to determine whether the connection time meets expectations, and the restart command is generated when it is determined that the connection time does not meet expectations. The antenna system as described in claim 1, wherein the control unit presets a plurality of restart time points, and the control unit outputs the restart command at the restart time points, wherein as a standby time of the antenna system changes Long, the time interval between these restart time points is increased by an exponential time interval method or a multiple time interval method. A method for restarting an antenna system, comprising: receiving a reference value group from an antenna corresponding to at least one switch in an on state in a switching unit; comparing the reference value group with an alarm threshold to determine Whether the reference value group meets expectations; and when the reference value group does not meet expectations, a restart command is output to restart the switching unit. The method for restarting an antenna system as described in claim 10, wherein the step of restarting the switching unit further includes: switching all the switches in the switching unit to the conductive state; receiving a return from each of the antennas Value; generate a selection command according to the better at least one of the return values and send it to the switching unit; and select the corresponding switch according to the selection command and maintain the switch-on state, and use the remaining ones The switch is switched to an open state. The method for restarting an antenna system as described in claim 11, wherein the step of generating a selection command based on at least one of the return values and transmitting the selection command to the switching unit further includes: sorting the return values Generating a sorting result; and selecting at least one of the returned values that is earlier in the ranking according to the sorting result to generate the corresponding selection instruction. The method for restarting the antenna system as described in claim 11 further includes: each time the switching unit is restarted several times, each time the control unit determines that the return value of each of the antennas does not match the alarm threshold It is expected that an alarm threshold adjustment procedure will be initiated. The method for restarting an antenna system according to claim 10, wherein the reference value group includes a previous reference value and a rear reference value, and the restarting method further includes: acquiring the previous reference value at a first time; at a second Time to obtain the post-reference value; calculate a difference between the post-reference value and the pre-reference value; and compare the difference with the alarm threshold and output the restart command to restart the switching unit when the difference does not meet expectations ; Where the alarm threshold is a degree of decrease corresponding to the reference value. The method for restarting an antenna system according to claim 10, wherein the reference value group includes a current positioning information and the alarm threshold is a previous positioning information, and the restarting method further includes: obtaining the current positioning information; and comparing the The current positioning information and the previous positioning information; wherein, when the current positioning information is different from the previous positioning information, the restart command is output to restart the switching unit. The method for restarting an antenna system according to claim 10, wherein the reference value group includes a current gravity sensing information and the alarm threshold is a previous gravity sensing information, and the restarting method further includes: obtaining the current gravity sensing Measuring information; and comparing the current gravity sensing information with the previous gravity sensing information; wherein, when the current gravity sensing information is different from the previous gravity sensing information, the restart command is output to restart the switching unit. The method for restarting an antenna system according to claim 10, wherein the reference value group is a connection time of the corresponding antenna, the alarm threshold is a preset connection time, and the restart method further includes: receiving as The connection time of the antenna corresponding to the switch in the on state; and comparing the connection time with the preset connection time to determine whether the connection time meets expectations; wherein, when the connection time does not meet When expected, output the restart instruction to restart the switching unit. The method for restarting an antenna system according to claim 10, which further includes a plurality of restart time points, the restart method further includes: outputting the restart command at the restart time points; wherein, a standby time becomes longer to An exponential time interval method or a multiple time interval method increases the restart time points.

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